Hi,
Who makes good domestic UPSes these days? Looking for about 500VA (need to put a power meter in to be sure) and 30 mins runtime.
But it's more about which make and possibly series are any good?
Would like a decent output too (proper sinusoidal).
Cheers,
Tim
Most small UPS's are designed with an up time of about 10 minutes at full load, ie long enough to see if the power comes back ina minute or two and long enough for things to shutdown nicely if it doesn't. So your looking at a >1500 VA unit.
Also be aware that UPS's are far more sensitive to overload than the mains. Switching on a CRT monitor did't bother the mains but the UPS would instantly shutdown.
Now that I've got at my APC Smart UPS 700 to stop it cooking batteries it "just works". It did before but would kill a set of batteries in 3 to 4 years. Charge rate far too high for the temperature of the batteries. In March 2014 I fitted a fan, reduced the charge rate and replaced the batteries., That set of batteries are still working fine. The cheapo PC slot exhaust fan has just needed to be replaced but that's only a fiver versus £50 ish for a new set of batteries...
Battery cooking is a well known trait of APC UPS's, so unless you willing to dive in and mod your new UPS or can find real evidence that a given model doesn't cook the batteries I'd avoid APC.
I replaced the batteries in my SU2200 three years ago, and they've held up since, I did check it wasn't overvolting them.
Looking at the UPS internal (43°C) and external (32°C) temperatures for the last few weeks, I suspect it doesn't de-rate the charge voltage for temperature as it's been locked at 54.05V
Yuasa seem to suggest decreasing float voltage by 3mV for every degree above 20°C
OK Thanks :) - I must get a power measurement before I work out the actual spec (500VA is a wild guess, I suspect it may be a good bit less).
I've heard of the battery cooking problem. Didn't know there was a setting to solve it though.
Although mods like this are what I'm trying to avoid - and are putting me off APC a tad.
OK - I guess Eaton MEM is the next "well known" one to look at?
Switching on a 19 inch CRT colour monitor whilst powering a 300W load (a desktop and server box fed via an Upsonic600 - I'm not *that* stupid!) didn't disturb my venerable SmartUPS2000 in the slightest despite the brief 20 or so amps degaussing transient "CLANG!!!" from the monitor. :-)
The more recent (less than 20 years old) APC SmartUPS series can be configured via their serial/USB interface to float charge at less than the default[1] 2.3v per cell setting, allowing you to chose a less corrosive 2.25v per cell (13.5v per 12v SLA) setting. I'm not sure, but I think even that ancient SmartUPS2000 of mine originally had such provision (I could look at but I could not touch any of the settings for some undetermined reason).
Luckily the VR4 pot allowed me to adjust the 55.5v setting (it had drifted up from my original 55.2v setting) down to 54.0v to save a recently acquired set of four 7AH SLAs bought cheap from my local Alarm company (I know the proprietor from our computer club days) from a premature demise.
The original capacity spec was for 17AH SLAs but I was recommissioning this UPS on the cheap to test the PGI 1200 B2 Parkside inverter genset's immunity from the leading current induced overvolting defect common to standard generators that use the raw output from a single phase 50Hz alternator driven at a notionally steadyish 3,000rpm with AVR control of the rotor field winding magnetisation current[2].
A significant downside with that SmartUPS700 is the 20 watts standby consumption *after* its battery pack has fully recharged and drawing mere micro-amps of charging current. At 15p a unit, that's about 26 quid a year. I retired it in favour of a BackUPS500 (quasi-sine wave 500VA/350W rated single 7AH SLA unit with a 2.7W standby consumption) which floats its battery at 13.49v in standby but raises this to 14v when plugged in and switched off - no wonder the battery lasts so long! It's only ever plugged in and switched off for a few hours after a battery change in order to quickly put a refreshing charge back into the battery. :-)
[1] This rather corrosive float charging voltage is chosen as the default merely to claim an extra 5 to 10% or so autonomy out of a brand new set of batteries (for the first 12 to 18 months at least) by way of 'Bragging Rights'.It's not just APC who are guilty of this, all the manufacturers use this trick (at least in the case of SoHo kit). You'd do well to RTFM and adjust the float voltage down to the 2.25v per cell mark. It might curtail the autonomy by 5 or 10% over that of a not yet fried battery pack but it'll pay dividends some 3 or 4 years down the line when you can expect to see at least another two or three years of life out of your 'consumable'.
[2] Your old fashioned emergency/work/leisure petrol generator is becoming more and more of a liability than an asset with modern lighting and other electronic loads now being far more prevalent than in those long distant days of incandescent lighting and electronic valved (vacuum tubed) radios and monochrome TV sets and suchlike.It doesn't surprise me too much to see the likes of Lidl selling 1KW rated inverter gensets for a mere 99 or 129 quid each (the later PGI 1200 B2 and its predecessor, the PGI 1200 A1 respectively).
Having recently tried three examples of Aldi's 2000W Workzone inverter gensets (at 290 quid a pop - about a 100 quid or so cheaper than other similar commodity inverter gensets), I can honestly say that these are absolutely s**te and not worth wasting any time or money on.
In my case (literally I suppose!), that's never been an issue with my ancient SmartUPS2000 since I'd acquired it 2nd hand at a radioham rally about twenty years ago sans the battery box it would normally have been clipped onto the top of. As a consequence, I've always used an external battery pack in an environment (my basement) where the ambient rarely exceeds 20 deg C (and rarely drops lower than 8 deg C).
Despite this lack of battery exposure to extremes of temperature, I've still suffered indecently short lives out of what the UPS manufacturers glibly refer to as a 'Consumable'. 'Consumable' my arse! However, for many years I'd had the float voltage set to 55.2v (which had drifted up to 55.5v by the time I decided to sacrifice another set of 'consumables' to APC's altar just recently) in the mistaken belief that this was the optimal float voltage setting for a 48v battery pack.
I'd been obliged to decommission it for lack of serviceable batteries some two or three years back. Shortly after which, I discovered that not only was 2.3v per cell destructive of the two sets of cheap 36AH SLI batteries (6 months of an unremitting 13.8v float charging regime being sufficient to ruin your typical car battery), it didn't do any favours for the typical SLA batteries specified for UPS duty either, which rather put me off the whole idea of trying to gain hours and hours worth of autonomy using a bloody expensive 100+ AH battery bank.
My previous experience with the alternative of backing up the UPS with a cheap petrol genset had been a rather frustrating one since the significant capacitive loading from the UPS (9.4?F across the mains input) had sent my 2.8KVA 'Aldi special' genset into a massive overvolting spree, ending only when the UPS gave up on bucking the excess "Mains Supply" voltage and switching to battery power. I don't think I need paint you a more detailed picture - I'm sure you can figure out the rest of the story just from that description alone.
When Lidl put their Parkside PGI 1200 B2 1KW inverter genset on offer just over two months ago, at a mere 99 quid it was an irresistible opportunity not to be missed by which to verify that it would at long last be possible to backup my UPS with a petrol generator that *wasn't* doomed to overvolt when supplying emergency power.
This did prove to be the case although I only got some 30 seconds run time before the genset cut out with an overload due to a loose alternator plug connection to its inverter module. This, however, was more than enough time to see me returning to Lidl for an exchange unit which wouldn't start until I disconnected the low oil sensor switch.
Not knowing this was a common stock fault with a stuck float switch at the time (I was worried it might have been a temperamental oil *pressure* switch) I returned this unit (after running a more extensive UPS compatibility test) for yet another exchange but the store was, by that time, out of stock. I got hold of the current one a week later from another store when I was by then, now wise to these two stock (and easily corrected) 'faults'.
So now at long last, I *can* provide emergency power backup with autonomy measured in hours and days rather than mere hours from 500 quid's worth or more of 'consumable' batteries alone.
Advice to anyone contemplating such an upgrade to their existing UPS emergency supply, the trick is to avoid not only the ordinary emergency generators but also that piece of s**te Workzone inverter genset, currently being peddled by Aldi, and choose only modern "Suitcase" inverter genset types for this task.
With modern LED lit homes, even those humble 1KW rated Parkside inverter gensets are likely all you'll need to keep not only *all* the lights on but power the CH/DHW circulator pump, zone valve(s) and controller, a couple of desktop machines, a UHD Smart TV, an ethernet switch or two and your modem router (and a DECT phone base station and a few USB chargers to keep your tablets and phones charged up).
A 1000W (cont.)/1200W (30s surge) rated inverter genset is probably a bit too marginal to include your typical fridge and freezer compressor starting loads even using manual power management scheduling - a chest freezer can go for 24 hours or more without power without risk of spoilage provided you're not delving into it more than two or three times a day. If you can schedule a 'fast freeze' run to drop the temperature below normal, it'll probably last for 48 hours or more before you need to repeat the cycle.
The fridge, otoh, assuming our larder fridge (Whirlpool) is typical of the breed, is going to be harder to manage this way with its 4 or 5 hour thermostatically controlled cycle and 1000 or so watts startup surge (67W/130VA running), so an effective solution would appear to be to use it like an old fashioned 'Ice Box' where you source your supply of ice from the freezer and leave the fridge unplugged for the duration.
The discouraging surge loading test result with the fridge rather put me off repeating the exercise for our Elcold chest freezer so I don't have any similar figures. In view of the "Use the fridge like an old fashioned Ice Box" option, fed with ice from the freezer, I now regret that omission.
It's just possible that its surge loading may not have been quite so bad so I might have a go at grabbing this data in the not too distant future with the analogue watt meter and a digital movie camera to record the startup readings as I'd had to do with the fridge.
Of course, it you use a modern fridge freezer with a VFD compressor, this eliminates the hefty startup surge of the traditional sealed induction motor and compressor, replacing it with a more efficient and steady 30 or 40 watt continuous load - problem solved! :-)
Thank you for that - very interesting and most informative :)
Buy a laptop.
That explains a lot, thanks.
Sorry, a basic question. Do these devices detract from energy efficiency? If leaving stuff on stand-by is frowned upon, is a UPS not even worse?
Yes they eat a little power
The energy police haven't busted down my door yet, I choose to pay a little extra to keep stuff running (last time I checked the event log it had supplied power 11 times in 14 months, some for seconds, others for tens of minutes).
That won't run my internet, wifi, home automation etc!
Don't care :)
Well, I do. I'm not spending any of my time trying to set up an energy efficient home only to have it undone by one appliance.
I was hoping for an answer to my question.
Well, yes - to some extent it will add a degree of inefficiency. That's unavoidable with any UPS.
The question is:
How do you value a small waste cost vs unavailable or possibly damaged IT equipment due to frequent power losses?
APC's SmartUPS 1000 claims 97% efficiency.
Let's be uncharitable and say a typical UPS is 90% and your IT load is
100W (that's a lot, an HP Microserver Gen8 is quoted at 50W - so I am adding a switch, modem and HA embedded controller.Your wastage there would be 10W.
At 15p/unit that is 3.6p/day or £13/year.
In over half the year, that heat is probably not wasted (contributing to home heating).
If the APC get's better than 95%, halve the above.
It's a very small number in the grand scheme of things.
Most routers are 12V so connect it to an old car battery.
It means you don't lose unsaved data in a power cut.
My main PC is a laptop :)
It's the rest of the stuff I'm concerned about...
Does youtube offer 'Steptoe & Son' up next for anyone else after that?
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